Electric fuse or cut-out.



No. 650,602. Patented May 29, |900.

' L. W.v DDWNES.

ELECTRIC FUSE 0R CUT-'UUT- (Apphcat on l d O t. 18 1899) (No Model.)

Inman/Zn 2'.

UNITED STATES ,i

P.errnnrrA Ormes.

LOUIS W'. DOYVNES, OF PROVIDENCE, RHODE SLAN.

ELECTRIC FUSE OR CUT-OUT.

SPECIFICATION forming part of Letters Patent N o. 650,602, dated May 29, 1900. Application filed October 18, 1899. Serial No. 733,988. (No model.)

ilo a/ZZ whom it 71mg/ concern.-

Be it known that I, LOUIS W. DOWNES, residing at the city of Providence, State of Rhode Island, have invented a new and useful Improvement in Electric Fuses or Cut- Outs, which improvement is fully set forth in the following specification.

The object of my present invention is to provide an electric fuse or cut-out of what is known in the art as the plug type, and which will possess all the desirable features of the fuse described in my United States Patent No. 569,373, dated October 13, 1896, the most important of which are the extreme accuracy of the fusing or blowing point for any given overload of current and non-arcing properties under any conditions. Vith this end in view, and also the object of providing a fuse of the plug type which can be cheaply manufactured and the parts of which can be readily assembledand separated, l have devised a structure which will be best understood by reference to the accompanying drawings. The fuses of the character herein described are particularly adapted for use on low-potential circuitsc-say from fifty to two hundred and fifty volts-and while in this construction l have embodied the principle of the air-space about the fuse-wire, as set forth in my former patent, the device possesses important structural features independent of the application of this principle to the plugtype fuse.

In the drawings, Figure l is a vertical sectional view of a plug adapted to be screwed into a socket of any suitable and well-known form carrying proper line terminals or contacts. Fig. 2 is a top view of the same with the cap or cover and the filling in the upper compartment of the plug omitted. Fig. 3 shows a section, at right angles to the section of Fig. l, and a bottom plan view of the cap. Fig. 4f is a vertical sectional view through a plug and a socket therefor, showing an e1nbodiment o f my invention somewhat dierent from that illustrated in Figs. l to 3. Fig.

5 is atop view of the plug shown in Fig. 4c with the cap and filling omitted and the conducting-plate, which bridges the upper open end of the plug, broken away at one end and Fig. G is a sectional view showing a conven= ient way of forming the air-spaceabout the fuse-wire.

Referring to Figs. l to 3, A represents a hollow plug made of a suitable non-conducting or insulating material, preferably procelain. lt is open at its upper end and closed at its lower end bybottom wall a, or, in other words, is cup-like in form. This plug consists of an enlarged head d at its upper or open end and a stem e at its lower or closed end of less diameter than the head d. The upper open end of the head d is bridged by a metallic conducting-plate f, and the upper edge of the head is provided with two arc-shaped eleva tions g g at opposite sides thereof, which lit into correspondingly-shaped or counterpart recesses -Z Z in the under side of the cap, as hereinafter referred to, thus insuring the placing of the cap on the plug in the proper position to enable a screw h, passing through an opening in the cap, to engage a screw threaded opening in the conducting-plate.

i is a screw-threaded sleeve closely fitting about the stem e and electrically connected with conducting-plate f by short wiresj, passing through vertical openings 7c in the head d. Said wires are soldered in openings at the ends of the conducting-plate f at their upper extremities and to the sleeve at their lower extremities. v

L is a cap or cover adapted to closethe up per end of the plug and having in its under face recesses l Z, adapted to receive the elevations g g on the plug, as already explained, and a centrally-elongated recess Z', adapted to t over the conductingplate f.

m is a fuse wire or link which is soldered at its upper end in an opening in the middleV of the conducting-platef and at its lower end to a small an gle-piece n, the latter being held against the inner face of the bottom wall a `by a screw 0, passing therethrough and at its outer end engaging and holding in place the contact-plate p, which engages in a correspondingly-shaped recess in the outer face of llowermost section to the uppermost section,

and thus forming shoulders l) and c, extend ing about the inner Wall of the chamber. The bottom q of a cylindrical cup made of a heavy paper, cardboard, or other suitable material rests against shoulder b and forms a diaphragm or partition dividing the space within the plug, and the side wall q2 of the same extends upwardly to the height of the upper shoulder c.

r is a diaphragm or partition of similar material resting against the upper edge of the Wall q2 and the shoulder c. It will thus be seen that the space Within the plug is divided into three compartments. The upper and lower compartments areY filled with a suitable material g3, preferably in a finely-divided state, (such as slaked lime,) the principal function of which is to provide a multitude of minute paths or interstices for the escape of the vapor or gas evolved upon the fusing or blowing out of the fuse link or wire m. It is of course understood that this f use-link penetrates the finely-divided material in the upper and lower compartments and passes through the air-space left between the diaphragms or partitions.

In assembling the fuse as thus constructed the fuse-link m, connected to the angle-plate fn, having been secured in place by the screw o, the lower compartment is filled with finelydivided material q3, and the cup-like cylinder qis then slipped down over the fuse-wire until it rests against theshoulderb. The diaphragm fr is now put in place in a similar way, and the compartment above this diaphragm is then filled with finely-divided material. The conducting-plate j' is next secured in place, as clearly shown in Fig. l, and fuse-wire m soldered thereto. Cap L is then secured in place over the open end of the plug by the screw /t in a manner which will be clearly understood. lVhile the construction of fuse shown in Figs. l to 3 is well adapted for capacities approximating from one to thirty amperes, it has been demonstrated that in fuses of larger capacities it is desirable in order to avoid heating to provide a more perfect and positive contact between the line-terminals on the terminal block or socket and the contacts on the plug than can well be secured with the construction already described. With this end in View I have devised the construction shown in Figs. 4 and 5, which will now be described.

B represents a terminal block or socket (partly broken away at one side) having a cylindrical opening b exten ding therethrough and intersecting a recess b2 in the underside of the block. A cylindrical metallic contactsleeve c is fixed within the opening b. This metallic sleeve has a plain smooth inner contact-surface and is soldered at one side to the upturned end of the metallic conductingstrip d', which is held in place in a recess e in one side of the block B by a set-screw f', passing upwardly from the recess b2. The

strip d leads to a binding-post g', which serves to secure one of the line-wires second binding-post h at the other side of the block serves to secure the other line-wire y. A conductor 't' leads from this latter bindingpost to a flexible metallic diaphragm or plate 7c', which covers the lower countersunk extremity of the opening or socket b'. A contact-plate Z2 is secured to the upper side of the diaphragm k and projects upwardly into the lower end of the opening D.

The plug C shown in Figs. 4 and 5 resembles the plug A of Figs. l to 3 as to its external arrangements, with the exception that (instead of the screw o) the screw m projects through Vcontact-plate n of the diaphragm k', whereby when the plugis turned in the socket said screw by engaging in vthe openings referred to tightly draws the contact-plate Z' of the socket upwardly and into close contact with the corresponding plate n on the plug, this operation being facilitated by the flexibility of the diaphragm, which is free to yield by reason of the countersunk lower end of the opening b. The stem of the plug Cis surrounded by a sleeve 0, having an outwardlyturned fiange o2 about its upper edge engaging under the head p. The outer cylindrical surface of the sleeve 0 is smooth and is adapted to make close frictional contact with the inner surface of the sleeve c of the socket.

As shown in Figs. 4 and 5, the conductingplate q after bridging the upper open end of the plug is bent about and under the edge of the head p', engaging in recesses r. At its inturned lower extremity s' it is soldered to the outturned flange o2 on the sleeve o. The cover T is held in place by screws t', passing therethrough and through openings in the conducting-plate q into nuts u', resting in recesses n' in the upper edge of head pl. By closely fitting these recesses the nuts are prevented from turning as the screws are inserted.

The manner of asscmblin g and dismembering the parts'of' the plug illustrated in Figs. 4 and 5, as Well as the manner of insertingit and withdrawing it from this socket, will be readily understood from the description already given.

It will of course be understood that any convenient form of block or socket other than that illustrated in Fig. 4 may be employed in connection with the plug shown in this figure. Instead of an air-space of the form shown in Figs. l and 4 said space may be of the form shown in Fig. 6. This may be secured by the use of ordinary capsules m2 m2, slipped over the fuse-wire m and telescoped together at their open ends and perforated at their closed ends, all as shown in Fig. 6. It is of course IOO IIO

understood that the filling is packed around f able means for providing the same may be employed. i

Having thus fully described my invention, what I claim as new isl. An electric fuse or cut-out consisting of a hollow cup-like plug having an enlarged part or head at its open end and a reduced v part or stem at its closed end, a contact-sleeve about the stem, a conducting-plate bridging the open end of the plug and bent at opposite ends about the side of the head into recesses formed in said side and electrically connected at its extremities to the contact-sleeve, a contact-plate on the end of the stem, a fuse-wire within the plug connecting the contact-plate with the conducting-plate, a cap or cover for closing the open end of the plug, and means for securing said cap to the conducting-plate. 2. In an electric fuse or cut-out, a hollow cup-like plug about t-he interior of which are formed two shoulders, diaphragms or partitions resting on said shoulders and dividing the interior space into three compartments of which the intermediate one constitutes an air-space, two contact surfaces or terminals on the plug, a fuse wire or link penetrating the three compartments and connecting the two contact-,surfaces on the plug, a filling of suitable material in the upper and lower compart-ments about the fuse-wire, and a cap or cover for closing the open end of the plug.

3. In an electric fuse or cut-out, a hollow cup-like plug the interior of which is divided into three sections of different diameters progressively increasing from the closed toward the open end thereof, thus forming two shoulders extending about the interior of the plug, two diaphragms or partitions of different diameters adapted to be introduced through the open end of the plug and to rest on said shoulders respectively, thereby dividing the interior of the plug into three compartments the intermediate one of which constitutes an air-space, two contact-surfaces on the plug, a fuse connecting said surfaces and penetrating the three compartments, a filling of suitable material in the upper and lower compartments about the fuse-wire, and a removable cover for the open end of the plug.

4. In an electric fuse or cut-out, a hollow cup-like plug the interior of which is divided into three sections of different diameters progressively increasing from the closed toward the open end thereof, thus forming two shoulders extending about the interior of the plug, a cup-like partition or diaphragm resting at its bottom on the lower shoulder with its side walls projecting upwardly to the height of the upper shoulder, and a second diaphragm or partition resting against the upper shoulder and against the upper edge of the side Walls of the lower diaphragm, the diaphragms or partitions thus dividing the interior of the plug into three compartments the intermediate one of which constitutes an air-space, two contact surfaces or terminals on the plug, a fuse- Wire penetrating the three compartments and connecting the two contact-surfaces on the plug, a iillin g of suitable material in the upper and lower compartments about the fuse wire, and a removable cover over the open end of the plug.

5. The combination with a terminal block having a plug opening or socket extending therethrough and counter-sunk at its lower end, a cylindrical contact sleeve having a plain smooth interior or contact surface and constituting one of the lineterminals, a flexible plate or diaphragm covering the lower end of the plug opening or socket, a contact-plate carried by said diaphragm and projecting upwardly into the bottom of the plugopening, of a plug, a cylindrical contact-sleeve about said plug having a plain smooth exterior surface adapted to closely 'fit the interior surface ot' the contact-sleeve when the plug is introduced into the socket, a contact-plate on the end of the plug adapted to bear against the contact-plate at the bottom of the socket, a screw projecting from the lower end of the plug and adapted to engage a screw-threaded opening through the contact-plate and diaphragm on the block, and a fuse-wire con-V necting the plate and sleeve contacts on the plug.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

LOUIS W. DOWNES. Witnesses:

JOHN HENsHAw, JAMEs H. THURsToN. 

